Energy generation by ram pressure in mortar and …e2s2.ndia.org/schedule/documents/abstracts/12335.pdfEnergy generation by ram pressure in mortar and artillery fuzes. ... • Electronic

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Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe

Energy generation by rampressure in mortar and artillery

fuzesNDIA E2S2 symposium & exhibition – may 12th 2011

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Outline• Introduction

• Functional principle of the generator

• Simulation with OpenModelica

• Results of the simulation

• Parameter studies

• Comparison between simulation and experimental results

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Introduction/ motivation• Electronic systems in fuzes need electrical power• Environment contains a lot of energy, which can be

converted into electric energy• Storage of batteries is a problem

– Loss of charge during storage

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Functional principle of the generator• Linear spring mass system• Induction of voltage in a coil due to magnet movement• External force due to ram pressure

– Magnet works like a valve: it opens and closes an outlet periodically

Magnet CoilSpring

xkV e ⋅=Basic equation:

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Generator model

Magnet (NdFeB)

CoilAir outletAir inletSpring

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Experimental fuze setup

Fuze casing (left) with energyharvesting generator

Fuze combined with energyharvesting generator

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Simulation with OpenModelica• Using the open source software ‘OpenModelica’• Object-oriented programming• Using differential equations for describing the single parts

of the model– Using coupling constant for electric coupling– Using compressible ideal gas model

• Numerical solving of a system of differential equations• About 50 parameters and over 120 variables

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Why OpenModelica?• Spring-mass model does not have a ram-pressure

dependency• Simulation of periodical opening of the outlet• Using compressible gas• Object oriented programming• Connects multiphysic equations

– electrical– mechanical– aerodynamic

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pressuresource

Inletvalve volume

magnet damperspring

internalresistanceinductivity

electromagneticcoupling

loadresistance

pressuresink

outlet valve

leakage

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Occurring ram pressure

Dependence of ram pressure on velocity and flight time

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Results of simulation

Pressure over time pressure over volume

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Pressure and voltage

voltage over timePosition of magnet over time

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Variation of ram pressure

pressure over volume voltage over time

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Variation of inlet and outlet

voltage over diameter ratio

• for high ratios voltage saturationoccur

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Power efficency

power over pressure pressure-volume-circle for different rampressure

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Comparison between simulation andexperimental results

• curve form is similar• frequency of the simulated curve is slightly to high

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Conclusions• Power can be increased by variation of system parameters• Power decreases with decreasing ram pressure• Available mechanical and electrical power decreases with

volume• Electrical power efficiency is about 0.1-2 % of the mechanical

power

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Thank you for your attention

Documents

Energy generation by ram pressure in mortar and …e2s2.ndia.org/schedule/documents/abstracts/12335.pdfEnergy generation by ram pressure in mortar and artillery fuzes. ... • Electronic